RFR(xs): 8204095: [TESTBUG] TestPrintReferences.java fails if multiple concurrent mark happens

[Kim Barrett]

> On May 30, 2018, at 4:15 PM, sangheon.kim at oracle.com wrote:
> 
> Hi all,
> 
> Can I have reviews for this tiny patch?
> 
> TestPrintReferences.java compares total time of a phase and sum of sub-phases.
> However it doesn't split values in different GCs so it could read total time from one GC and sum of sub-phases from followed GC.
> This patch excludes other GCs from the first one so we are not affected by following GC values.
> 
> CR: https://bugs.openjdk.java.net/browse/JDK-8204095
> Webrev: http://cr.openjdk.java.net/~sangheki/8204095/webrev.0
> Testing: hs-tier1 and local tests.
> 
> Thanks,
> Sangheon

Looks good.